Extensive work over the past years has demonstrated the immense value and novel chemical nature of cyclic polyethers. For example, see "Synthetic Multidentate Macrocyclic Compounds", edited by Reed M. Izatt and James J. Christensen, Academic Press, New York (1978) and "Progress in Macrocyclic Chemistry, Volume 1", edited by Reed M. Izatt and James J. Christensen, John Wiley and Sons, New York, (1979), for ample description of the structures and nomenclature related to these cyclic polyethers.
As recently as 1978 J. S. Bradshaw [in "Synthetic Multidentate Macrocyclic Compounds," ed. R. M. Izatt and J. J. Christensen, Academic Press, 1978, p. 53] referred to "the so-called crown class of compounds first prepared by Pedersen (1967)." On p. 10 of the same book C. J. Pedersen stated:
Only a few publications prior to 1967 referred to polyethers, and none of them considered the possibility of their forming complexes with the salts of the alkali and alkaline earth metals. Of the previously reported compounds, the most closely related to the crown compounds were 2,2,7,7,12,12,17,17-octamethyl-21,22,23,24-tetraoxaquatrene, C.sub.28 H.sub.32 O.sub.4, made by condensing acetone with furan (Ackman et al., 1955); 2,3,12,13,22,23-tribenzo-1,4,11,14,21,24-hexaoxacyclotriaconta-2,12,22-tri ene (tribenzo-30-crown-6), C.sub.36 H.sub.48 O.sub.6, and 2,3,12,13-dibenzo-1,4,11,14-tetraoxacycloeicosa-2,12-diene (dibenzo-20-crown-4), C.sub.24 H.sub.32 O.sub.4 (FIG. 4, XIX) (Luttringhaus and Sichert-Modrow, 1956). Cyclic tetramers of ethylene oxide (Stewart et al., 1957) and propylene oxide (Down et al., 1957, 1959) had also been synthesized previously.
However, see also: A. Luttringhaus and K. Ziegler, Ann., 528, 155 (1937); A. Luttringhaus, Ann., 528, 181, 211, 233 (1937); R. Adams and L. N. Whitehill, J. Am. Chem. Soc., 63, 2073 (1941); W. J. Toussaint and D. R. Jackson, unpublished work, 1945, reported by R. F. Holden, in "Glycols," ed. G. O. Curme, Jr., and F. Johnston, A.C.S. Monograph Series, 1952, p. 274; J. B. Rose, J. Chem. Soc., 542, 546 (1956); J. L. Down, J. Lewis, B. Moore, and G. Wilkinson, Proc. Chem. Soc., 209 (1957); J. L. Down, J. Lewis, B. Moore, and G. Wilkinson, J. Chem. Soc., 3767 (1959); R. O. Colclough and K. Wilkinson, J. Polymer Sci. (C), No. 4, 311 (1963). Note especially the report of pentamethyl-15-crown-5 and hexamethyl-18-crown-6 by Holden and the comment by Down, Lewis, Moore, and Wilkinson that "the chelating possibility of this ether [tetramethyl-12-crown-4] is obviously important."
J. S. Bradshaw and P. E. Stott, Tetrahedron, 36, 461 (1980) have summarized work on procedures which are variatons of the Williamson ether synthesis.
Additional, recent, reports include: M. Okahara, M. Miki, S. Yanagida, I. Ikeda, and K. Matsushima, Synthesis, 854 (1977); R. O. Trucks and E. C. Steiner, U.S. Pat. No. 4,113,739 (1978); M. Okahara, I. Ikeda, and S. Yanagida, Japan Patent Publications 98985 (1978) and 119483 (1979); L. Mandolini and B. Masci, Synth. Comm., 9, 851 (1979); N. Kawamura, M. Miki, I. Ikeda, and M. Okahara, Tet. Lett., 535 (1979); P.-L. Kuo, N. Kawamura, M. Miki, and M. Okahara, Bull. Chem. Soc. Japan, 53, 1968 (1980); I. Ikeda, S. Yamamura, Y. Nakatsuji, and M. Okahara, J. Org. Chem., 45, 5355 (1980); B. Czech, Tet. Lett., 4197 (1080). Bradshaw and Stott also discuss an alternate method based on direct acid catalyzed oligomerization of ethylene oxide using a cationic template.
However, it is obvious that only a direct process from the cheap petrochemical raw material ethylene oxide can make possible the large scale industrial preparation of these valuable cyclic ethers.
In applicants co-pending U.S. Ser. No. 248,532, filed Mar. 22, 1981, a process is disclosed for preparing cyclic polyethers from alkylene oxides in the presence of a catalyst selected from the group consisting of alkali halides, alkaline earth halides and mixtures thereof.
The use of ethylene carbonate as an ethoxylating agent has been reported in the literature; see W. W. Carlson and L. H. Crelcher, J. Amer. Chem. Soc., 69, 1952 (1947) and T. Yoshino, S. Inaba, H. Komura, and Y. Ishido, Bull. Chem. Soc. Japan, 47 (2), 405 (1974).
The decomposition of ethylene carbonate in the presence of alkali halides is disclosed in an article by Y. Ishido, H. Tsutsumi, and S. Inaba, J. C. S. Perkin I, 521 (1977) and by A. L. Shapiro, S. Z. Levin, and V. P. Chekhovskaya, Zh. Org. Chem of U.S.S.R., 5 (2), 207 (1969). In addition the article by Shapiro et al., discloses that the alkali metal halides decompose ethylene carbonate to form ethylene oxide and carbon dioxide. The formation of polyethylene oxide is disclosed as the only product formed when lithium, sodium, or potassium fluoride are employed. The use of chlorides of lithium, sodium, potassium, and cesium and the bromides and iodides of lithium, sodium and potassium is disclosed to give ethylene oxide and polyethylene oxide when employed at 200.degree. C. (see Table I on page 201 thereof). Other reports of the reaction of cyclic alkylene carbonates with halide salts include E. D. Bergmann and F. Shahak, J. Chem. Soc. (C), 899 (1966); Y. Wu, U.S. Pat. No. 4,111,965 (1978); T. Yoshino, S. Inaba, and Y. Ishido, Bull. Chem. Soc. Japan, 46, 553 (1973); T. Yoshino, S. Inabe, H. Komura, and Y. Ishido, JCS Perkin 1, 1266 (1977); A. Hilt, J. Trivedi, and K. Hamann, Makromol. Chem., 89, 177 (1965); E. Schwenk, K. Gulbins, M. Roth, G. Benzing, R. Maysenholder, and K. Hamman, Makromol. Chem., 51, 53 (1962); A. M. Ryzhenkov, A. L. Shapiro, V. S. Mozhenko, in Alkilenkarbonaty, ed. V. V. Shipikin, Leningrad, 1975, p. 87; A. L. Shapiro, V. P. Chekhovskaya and B. L. Vorob'ev, ibid., p. 94; A. L. Shapiro, I. S. Lyubovskii, V. P. Chekhovskaya and B. L. Vorob'ev, ibid p. 103; S. Sarel, T. Rand-Meir, and A. Poles, Israel J. Chem., 2, 237 (1964); K. Gulbins, G. Benzing, R. Maysenholder, and K. Hamann, Chem. Ber., 93, 1975 (1960); D. Grobelny, P.Maslak, and S. Witek, Tet. Lett., 2639 (1979); A. Lemaire, K. J. Schroader, and M. F. Reed, J. Labelled Compd. Radiopharm., 13, 211 (1977) [Chem. Abstr. 87, 52682q (1977)]. None of these publications reports the formation of a cyclic polyether in these reactions.